A hypobromous acid or a water-soluble salt thereof can exhibit a high sterilization effect or anti-microbial effect in liquid to be treated having a high pH (e.g. hot spring water from a highly alkaline spring, white water or open-circulating cooling water in a papermaking machine at a pulp and paper mill and the like). Therefore, a hypobromous acid or a water-soluble salt thereof are used as for disinfection or as a slime control agent for such liquid to be treated.
Conventional methods of producing a hypobromous acid or a water-soluble salt thereof include the following reported production methods:                blowing ozone into a solution containing bromide ions to convert the bromide ions to hypobromous acid (refer to Patent Document 1);        adding a hypochlorite and a bromide to a liquid to be treated, whereby the resulting reaction forms a hypobromite (refer to Patent Documents);        making a bromide present in the liquid to be treated, and then adding aqueous peracetic acid or aqueous hydrogen peroxide to form a hypobromite (refer to Patent Document 3); and        with a sulfamate compound as a stabilizer, pre-mixing a hypochlorite and a bromide to produce a stable hypobromite (refer to Patent Documents 4 and 5).        
Patent Document 1: Japanese Patent Application “kokai” No. 5-213706
Patent Document 2: Japanese Patent Application “kokai” No. 60-129182.
Patent Document 3: Japanese Patent Application “kohyo” No. 2002-86155
Patent Document 4: Japanese Patent Application “kohyo” No. 11-506139
Patent Document 5: Japanese Patent Application “kohyo” No. 501869